The emphasis of our recent work has been on purification and properties of several asparaginases. We have partially sequenced E. coli asparaginase, first isolated here, and purified several other asparaginases, including one without anti-tumor activity from a mould, Fusarium tricinctum. Our objectives now are to complete the sequence of E. coli asparaginase; establish the biochemical basis for the fact that the Fusarium enzyme does not have anti-tumor activity, whereas E. coli asparaginase does; and modify the properties of E. coli asparaginase by glycosylation. In this last connection, we plan to extend our preliminary experiments on covalent attachment of l-aminoglucose to chymotrypsinogen and asparaginase, by first attaching suitable sugars to asparaginase by chemical means, and then using glycosyl transferases to add other sugar units, attempting to prepare glycosylated enzyme with side-chains terminating in galactose and sialic acid, typical of endogenous plasma glycoproteins. Asparaginase modified in this or related ways might be a more effective anti-tumor agent. It also seems likely that such studies would be of importance in other areas of glycoprotein biochemistry.